Dispersant for suspension polymerization of vinyl chloride resin and PROCESS FOR ITS PREPARATION

摘要

1. A dispersant for suspension polymerization, comprising modified polyvinyl alcohol having a component unit represented by the following chemical formula (A), and characterized by a saponification value of 75% (mol.) Or more and less than 90% (mol.) , absorbance in the wavelength region of 280 nm, as defined for the water or mixed water and methanol solution at a concentration of 0.2% (wt.) in the range from 0.5 to 2.5, and a viscosity, as determined by indicated in the document JIS K 6726, component 4 mPas or more and less than 30 mPas s.gde Hee Hmogut be identical to each other or different from each other and represent an alkyl group, characterized by the number of carbon atoms ranging from 1 to 12, a hydrogen atom or metal, g is an integer ranging from 1 to 3.2. A dispersant for suspension polymerization according to Claim. 1, characterized by an optical density in the wavelength region of 325 nm, by definition at 20 ° C for water or mixed water and methanol solution at a concentration of 0.2% (wt.) In the range of from 0.02 to 0,20.3. A dispersant for suspension polymerization according to Claim. 1 or 2, characterized by a cloud point as defined for the aqueous solution at a concentration of 4% (wt.) Of 50 ° C and bolee.4. Vinyl chloride resin having a bulk specific density was 0.05 g / cc more, and the resultant dispersion in water of the vinyl chloride monomer or a monomer mixture containing vinyl chloride monomer, by using a dispersant for suspension polymerization according to any one of claims. 1-3